Joining Obama to pick up ribs was Sen. Benjamin Cardin, who — coincidentally enough — faces a challenge in the April 3 Maryland Democratic primary from state Sen. C. Anthony Muse of Prince George’s County.

Obama endorsed Cardin for reelection back in November, when it was already known that Muse was likely to run. Maryland Democratic leaders have also closed ranks behind the incumbent, prompting some complaints from Muse that he was not being given a fair shot.

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The full pool report on Obama’s lunch stop, from the Washington Post’s David Nakamura, is after the jump.

The pool report:

After the community college speech, POTUS made an unscheduled lunch stop with Sen. Ben Cardin at the Texas Ribs & BBQ restaurant in Clinton, Md. He surprised the lunch crowd, sitting at wooden paneled tables. The restaurant sign outside advertised corn beef and cabbage on Friday, Saturday and Sunday.

Obama and Cardin sidled up to the takeout counter inside and POTUS inspected a menu as the cashier attempted to hand him a bag of someone else’s food. Couldn’t hear what POTUS ordered but heard him say: “hot sauce; got be hot. Do you want me to pay up now or pay later?”

“Later,” the cashier said.

“I am going to have to pay so don’t try getting sneaky on me,” said Obama, who then went with Cardin to greet diners while his food was being prepared.

One group of diners included some military folks and a man told POTUS he had helped fly a him during ‘08 campaign in military aircraft. Obama thanked him.

The restaurant featured license plates on the wall from Texas, Arizona and Maryland. Also trophies. A leather horse saddle. A wooden Jack Daniels sign. POTUS took pics and signed autographs with diners.

He asked: “You guys taking a little lunchbreak? What’s your name?”

Cardin dressed in suit blue dress shirt striped tie.

ESPN on TV — skiing competition.

“Thanks for your service. I’m standing between you and the last bite,” he said to some diners who worked at Andrews Air Base.

Obama picked up his takeout order - two slabs of babyback ribs--and then greeted supporters who had gathered outside. He did not respond when your pooler shouted a question about Hamid Karzai’s demand that U.S. troops remain out of Afghan villages and stay on base in outposts.